This test will faill, but I don't know how to make a relevant test.

If I make a mock, this test can pass, but will this means something ?
This test could pass with a simple Memcached storage like this one (tested on my ubuntu server) :
```php
        $zfStorage = new Memcached(array(
            'servers' => array(
                'localhost'
            )
        ));
```

So the same test will pass or fail depending of the storage although they all implement the same interface. :dizzy_face: